From her slightly scruffy appearance, she looks to be starting to molt, which is a stressful time. The first time is around 18 months old. Adding to that stress is she is in a new home. New dirt, may expose her to a new strain of coccidiosis that she has not built up a tolerance for yet. Her tail is down which is a sign of a hen who feels bad, and she might also be having a reproductive disorder or having trouble laying an egg. Usually, a hen who is molting will stop laying for awhile. The things I would do is to offer some soft scrambled egg and a little watery chicken feed. Check her crop early in the morning before she eats or drinks to see if her crop has emptied. Consider worming her with Valbazen or albendazole, or 10% fenbendazole liquid goat wormer. Start some Corid (amprollium) 2 tsp of the liquid or 1.5 tsp of the powder per gallon of water for 5 days. That is the maximum dosage and treat all birds. Is Corid what you have started for treatment of coccidiosis?